The subject matter disclosed herein generally relates to rotor control systems and, more particularly, to connector assemblies for rotor head swashplates.
Control of a rotary-wing aircraft, such as a vertical takeoff and landing (VTOL) aircraft or helicopter, is affected through cyclic and collective pitch control. Blade pitch control of a rotary-wing aircraft main rotor system is typically achieved through a swashplate assembly which transfers the motion of non-rotating control members within a stationary field to the rotating members within a rotational field.
The swashplate assembly generally includes two rings connected by a series of bearings with one swashplate ring connected to the airframe/gearbox (stationary field), and the other swashplate ring connected to a rotor hub (rotational field). Apart from rotary motion, the rotationally stationary swashplate ring and the rotational swashplate ring otherwise move as a unitary component.
Swashplate assemblies may be employed with or on helicopter rotor heads as a means of controlling blade pitch via an aircraft's fixed controls. The swashplates may typically include a rotating element or field that is directly linked to the blades in the rotor head and a stationary or fixed element or field that does not rotate. The rotating element of the swashplate may be connected to the blades by one or more pitch control rods or links. The rotor head may thus rotate the rotating element of the swashplate by pulling or forcing the connected rotating element to rotate through these pitch control rods or links. However, such configuration may result in dynamic instability within the system.
Thus, connector assemblies have been employed to drive the rotating element of the swashplate, thereby reducing the possibility of dynamic instability. Traditional connector assemblies may include hinge-like or scissor mechanisms. A pair of jointed connector assemblies may be included in the system. One of the connector assemblies may be configured to prevent the stationary or fixed element from rotating with the rotating element. Another connector assembly may be configured to connect the rotating element of the swashplate to a rotating shaft or head of a rotor. In this way, the rotating element of the swashplate will rotate at the same angular speed as the blades, which are also connected to the rotating shaft or head of the rotor, and are driven thereby.
The connector assemblies enable the swashplate assembly to be slid along the rotor shaft, thus enabling changes in position and orientation, while maintaining a mechanical connection between the rotating elements of the aircraft and the rotating element of the swashplate. Changes in position and orientation of the swashplate impacts the pitch of the blades of an aircraft thus enabling flight control.